Self-contained electrostatic air/oil separator for aircraft engine

Abstract

An air/oil separator for use in a gas turbine engine includes a centrifugal separation stage in fluid communication with a downstream electrostatic separation stage. The centrifugal separation stage rotationally drives an electric generator to power the electrostatic separation stage.

1. An air/oil separator for use in a gas turbine engine comprising a centrifugal separation stage in fluid communication with a downstream electrostatic separation stage, the centrifugal separation stage rotationally driving an electric generator to power the electrostatic separation stage. 
   
   
     2. The air/oil separator as defined in  claim 1  wherein the centrifugal separation stage comprises a turbine rotor rotated by an air/oil mixture flow to be processed in the centrifugal separation stage. 
   
   
     3. The air/oil separator as defined in  claim 1  wherein the electrostatic separation stage comprises a labyrinth path. 
   
   
     4. The air/oil separator as defined in  claim 3  wherein the electrostatic separation stage comprises a flow nozzle for injecting the air/oil mixture flow from the centrifugal stage into the labyrinth path. 
   
   
     5. The air/oil separator as defined in  claim 4  wherein a DC voltage is applied over the flow nozzle and the labyrinth path, with a positive polarity on the flow nozzle. 
   
   
     6. An air/oil separator for use in a gas turbine engine comprising:
 a turbine rotor, disposed in a passage and adapted to be rotated by an air/oil mixture flow passing through the passage, to separate oil from the air/oil mixture flow; 
 means for further directing the air/oil mixture flow after having passed through the turbine rotor; 
 a labyrinth path defined by electrically conductive walls, the labyrinth path having an inlet for receiving the air/oil mixture flow directed by the means, and a first outlet for discharging substantially purified air; 
 means for electrically, positively charging the air/oil mixture flow with respect to the conductive walls of the labyrinth path before the air/oil mixture flow enters the labyrinth path, to further separate oil from the air/oil mixture flow in the labyrinth path; and 
 means for collecting the separated oil from the respective passage and labyrinth path. 
 
   
   
     7. The air/oil separator as defined in  claim 6  wherein the means for further directing the air/oil mixture flow comprises an electrically conductive flow nozzle. 
   
   
     8. The air/oil separator as defined in  claim 7  wherein the means for electrically, positively charging the air/oil mixture flow with respect to the conductive walls of the labyrinth path, comprises a source of DC voltage connected to the respective electrically conductive flow nozzle and the electrically conductive walls of the labyrinth path with positive polarity on the electrically conductive flow nozzle. 
   
   
     9. The air/oil separator as defined in  claim 8  wherein the source of DC voltage comprises an AC generator driven by the turbine rotor and a voltage conditioner for converting an AC voltage obtained from the AC generator into a DC voltage. 
   
   
     10. The air/oil separator as defined in  claim 9  wherein the AC generator comprises a permanent magnetic rotor integrated with a shaft of the turbine rotor and a stator of electric conductor windings. 
   
   
     11. The air/oil separator as defined in  claim 6  wherein the means for collecting the separated oil comprises a first drainage outlet defined in a lower portion of the passage, receiving the turbine rotor and a second drainage outlet defined in a lower portion of the labyrinth path. 
   
   
     12. The air/oil separator as defined in  claim 6  wherein the means for collecting the separated oil comprises a jet pump to collect the separated oil accumulated in the respective passage receiving the turbine rotor and in the labyrinth path and to then deliver the collected oil to an oil tank. 
   
   
     13. A method for separating oil from an air/oil mixture in a gas turbine engine comprising:
 1) directing a flow of air/oil mixture into a centrifugal separation stage to centrifugally separate a first portion of oil from the air/oil mixture; 
 2) electrically and positively charging the low of air/oil mixture exiting from the centrifugal separation stage; and 
 3) further directing the electrically, positively charged flow of air/oil mixture into an electrostatic separation stage defined by an electrically grounded labyrinth path, to electrostatically separate a second portion of oil from the air/oil mixture. 
 
   
   
     14. The method as defined in  claim 13  wherein the flow of air/oil mixture is directed under a pressure to impinge on a rotor of the centrifugal separation stage, thereby driving the centrifugal separation stage to rotate. 
   
   
     15. The method as defined in  claim 13  comprising a step of operating an electric generator by means of the centrifugal separation stage in order to electrically and positively charge the low of air/oil mixture exiting from the centrifugal separation stage. 
   
   
     16. The method as defined in  claim 13  comprising a step of collecting the first and second portions of separated oil using a jet pump.